"HIV Susceptibility and Pathogenesis in the Female Genital Tract" is designed to study mechanisms of HIV infection that are unique to women. Its four investigator initiated projects are strongly interactive and focus on HIV in the female genital tract. Project I, Microscopic Analysis of the Interaction of HIV and the Human Female Genital Tract (Thomas Hope, PhD, NWU), studies HIV interaction with tissue and mucous in the female genital tract. Project II, HIV and Female Genital Tract Flora (Greg Spear, PhD, RUMC), studies the effect of bacterial infection in the genital tract on susceptibility to HIV infection. Project III, HIV-Specific Immunity in Highly Exposed Uninfected Women (Richard Novak, MD, UIC and Linda Baum, PhD, RUMC), studies the potential development of protective mucosal immunity that results from sexual exposure to HIV. Project IV, Role of Estrogen in HIV Transmission and Pathogenesis (Lena AI-Harthi, PhD, RUMC), studies the effects of estrogen mediated leukocyte activation and Wnt/p-catenin signaling on HIV transmission. Four cores foster the collaborative interactions between projects. Core A (Administrative Core) is directed by the Program Project PI, Alan Landay, PhD, RUMC. Core B (Clinical Core) directed by Audrey French, MD, Cook County, will provide samples from established cohorts of HIV infected women: the Women's Interagency HIV Study (WIHS), the Women at Heterosexual Risk Cohort (WISH) and HIV infected women from Rwanda (RWISA). When necessary, women of interest from these established cohorts will be recruited to provide additional samples. Core C (Tissue Culture and Virology Laboratory Core) directed by Nell Lurain, PhD, RUMC, will perform experiments with the HIV tissue explant replication model, prepare molecular and virologic reagents, and maintain a specimen repository. Core D (Biostatistics/Epidemiology Core) directed by Elizabeth Golub, PhD, JHU, will help project investigators plan studies and evaluate results. The synergy of effort among projects and cores is evident in aims that require participation of multiple investigators and resources provided by the cores. This PO1 will improve our understanding of factors that enhance or inhibit sexual transmission of HIV and will lead to the development of innovative interventions to prevent HIV. RELEVANCE: The 4 projects and 4 cores of this program project will provide novel insights into the pathogenesis of HIV disease in women. All of these studies utilize a novel in vitro explant model that mimics HIV infection in the human female genital tract and samples from patient cohorts. They will provide potentially important information that will lead to the development of new approaches for HIV prevention and therapy in women. PROJECT 1: Microscopic Analysis of the Interaction of HIV and the Human Female Genital Tract (Project Leader: HOPE, T) PROJECT 1 DESCRIPTION (provided by applicant): Twenty-five years since the discovery of HIV-1, the underlying biological mechanism(s) of male-to-female sexual transmission remain unclear. To initiate infection, HIV must traverse the protective outer genital epithelial barriers, establishing infection in underlying immunocompetent target cells. To study the interactions of individual HIV virions with mucosal epithelial barriers, we developed a novel system comprising genital tissue explants and fluorescent microscopy. A difficult aspect of fluorescent microscopic analysis of tissue sections is the high background autofluorescence. To avoid this problem, we utilize HIV labeled with a photoactivatable form of green fluorescent protein (GFP). Tissue sections are initially scanned to define background autofluorecence. The field of view is then photoactivated, followed by a second scan. Viral particles appear as new signals observed only after photoactivation. Using this system we find that HIV can enter both the squamous ectocervical epithelium and the columnar endocervical epithelium in human explants. Future studies will analyze vaginal and uterine tissue. Virions are observed penetrating to depths that would facilitate contact with HIV targets such as Langerhans cells, macrophages, dendritic cells and CD4+ T cells. We find that the virus is primarily localized in interstitial spaces between cells in the squamous epithelium. This suggests that virus has the ability to move within the intact mucosal epithelia to encounter potential target cells of infection. Related studies will determine how cell-associated virus interacts with the tissues of the female genital tract. The specific aims seek to 1) define the interaction of HIV with the intact squamous epithelium of the ectocervix and vagina, 2) define the interaction of HIV with the intact columnar epithelium of the endocervix and uterus, 3) characterize the interaction of HIV with cervical mucous, and 4) determine how exogenous factors such as inflammation and other local environmental factors modulate the interaction of HIV with the mucosal epithelium leading to increased or decreased infection. The completion of these aims will increase our understanding of the underlying mechanism(s) of HIV sexual transmission. This information can then be utilized in the development of vaccines and microbicides designed to prevent HIV. RELEVANCE: There is currently a large effort to develop microbicides and vaccines to prevent the sexual transmission of HIV. Yet we currently do not understand in much detail how HIV is sexually transmitted. The studies propose here seek to reveal novel details of how HIV interacts with the human female genital tract leading to infection. This information will be invaluable in the development of strategies to prevent HIV transmission.